preparation of left ventricular outflow tract (lvot) from porcine heart for cannulation 

搭載型ブタ大動脈弁の流体力学的特性の評価

Aortic valve disease represents a significant public health burden, particularly aortic stenosis, which affects 9 million people worldwide1. Strategies to address this disease are currently evolving and include aortic valve repair and aortic valve replacement. In the pediatric population especially, there is a significant incentive to repair rather than replace the valve since currently available prostheses are prone to structural valve degeneration (SVD) and are not growth tolerant, requiring reoperation for re-replacement as the patient grows. Even the Ross procedure, which replaces the diseased aortic valve (AV) with the native pulmonary valve (PV), requires a prosthesis or graft in the pulmonary position that is also subject to SVD and often limited growth tolerance2. New approaches to aortic valve disease are being developed, and there is a need for testing in a biologically relevant context prior to application in a large animal model.
We have developed a method for testing a porcine AV that can provide insights into the function of the valve before and after an investigational procedure or application of a novel medical device. By mounting the porcine AV on a commercially available pulse duplicator machine, we are able to compare the hydrodynamic characteristics that are commonly used in the investigation and ultimately approval of valve prostheses, including regurgitation fraction (RF), effective orifice area (EOA), and mean positive pressure difference (PPD)3,4. The intervention can then be fine-tuned in a biologically relevant context before use in a large animal model, thus limiting the number of animals needed to produce a procedure or prosthesis that can be used in humans. The hearts used for this experiment can be obtained from the local abattoir or waste tissue from other experiments, so it is not necessary to sacrifice an animal solely for the purposes of this experiment.
In our work, we used this method to develop a novel patch material for valve repair and replacement. We tested the hydrodynamic function of a variety of patch materials by performing an aortic valve neocuspidization procedure (Ozaki procedure5,6,7) on porcine AVs and testing them in the pulse duplicator before and after the procedure. This enabled us to fine-tune the material based on its hydrodynamic performance. Thus, this method provides a platform for hydrodynamic testing of experimental procedures and novel medical devices for use on the AV prior to application&#160;in a large animal model.

著者スポットライト:大動物実験に着手する前に心臓手術試験を進める 

実験的大動脈弁処置および新規医療機器の流体力学的試験のための ex vivo 豚モデル

Limited options exist for testing new cardiac procedures and investigative medical devices before use in a large animal model. Our protocol provides the opportunity to fine-tune such procedures and devices in a biologically and anatomically relevant context prior to embarking on large animal studies. Other techniques for mounting an aortic valve on a pulse duplicator require inserting or fixing a rigid structure to the aortic valve annulus, thus distorting the valve's hydrodynamic properties.Our protocol offers an innovative way to cannulate the LVOT so that all measured hydrodynamic properties are valid. This method is designed to assess the viability of leaflet substitution materials for use as a valve repair patch or prosthesis. It is a pivotal tool for our future research in which we are developing biomimetic polymeric materials for use as durable valve substitutives with native tissue, like mechanical and hydrodynamic properties.

Watch this Scientific Journal Video about Preparation of Left Ventricular Outflow Tract LVOT from Porcine Heart for Cannulation at JoVE.com

Preparation of Left Ventricular Outflow Tract (LVOT) from Porcine Heart for Cannulation   

ブタの心臓からのカニューレ挿入のための左心室流出路(LVOT)の調製 

まず、軟肉切除術後に新鮮なブタ心臓標本を収集します。メッツェンバウムのハサミで大動脈から肺動脈を解剖し、心室組織が見えるまで切断します。次に、左右の冠動脈を解剖し、副鼻腔を狭くすることなく、大動脈洞から起点にシルクタイを使用して結紮します。絹のタイの遠位の冠状動脈を切除します。メッツェンバウムのはさみを使用して、肺動脈弁の基部にある大動脈と肺動脈の間の右心室を切開します。前方から始めて、脳室内中隔に沿って円周方向に切開を続け、右心室の自由壁を取り除きます。心房間中隔に沿って三尖弁輪を後方に切開し、右心房組織をすべて切除します。次に、メッツェンバウムのハサミを使用して、大動脈と平行な右肺静脈口から左心房を切開します。僧帽弁の前外側交連に向かってこの切開を続けます。大動脈と僧帽弁輪の3ミリメートルの心房組織のカフを円周方向に維持しながら、余分な左心房組織をトリミングします。次に、前外側乳頭筋を損傷することなく、僧帽弁の前外側交連を介して左心室に切開を伸ばします。脊索腱を前外側乳頭筋から後僧帽弁尖に分割し、前僧帽弁尖への付着物を保存します。切開部を心臓の頂点まで伸ばします。乳頭筋の下の余分な左心室組織をトリミングし、両方の乳頭筋を温存します。

preparation-left-ventricular-outflow-tract-lvot-from-porcine-heart

Research

JoVE Journal

Bioengineering

Preparation of Left Ventricular Outflow Tract (LVOT) from Porcine Heart for Cannulation 

89 ビュー.  Columbia University Medical Center. まず、軟肉切除術後に新鮮なブタ心臓標本を収集します。メッツェンバウムのハサミで大動脈から肺動脈を解剖し、心室組織が見えるまで切断します。次に、左右の冠動脈を解剖し、副鼻腔を狭くすることなく、大動脈洞から起点にシルクタイを使用して結紮します。絹のタイの遠位の冠状動脈を切除します。メッツェンバウムのはさみを使用して、肺動脈弁の基?...

ビデオ: Preparation of Left Ventricular Outflow Tract (LVOT) from Porcine Heart for Cannulation   

An Ex Vivo Porcine Model for Hydrodynamic Testing of Experimental Aortic Valve Procedures and Novel Medical Devices

The options for testing new cardiac procedures and investigative medical devices prior to use in an animal model are limited. In this study, we present a method for mounting a porcine aortic valve in a pulse duplicator to evaluate its hydrodynamic properties. These properties can then be evaluated before and after the procedure under investigation is performed and/or the investigative medical device is applied. Securing the inflow segment presents some difficulty owing to the lack of circumferential myocardium in the left ventricular outflow tract. This method addresses that issue by securing the inflow segment using the anterior leaflet of the mitral valve and then suturing the left ventricular free wall around the inflow fixture. The outflow segment is secured simply by inserting the fixture into an incision in the superior aspect of the aortic arch. We found that specimens had significantly different hydrodynamic properties before and after tissue fixation. This finding induced us to use fresh specimens in our testing and should be considered when using this method. In our work, we used this method to test novel intracardiac patch materials for use in the valvular position by performing an aortic valve neocuspidization procedure (Ozaki procedure) on the mounted porcine aortic valves. These valves were tested before and after the procedure to assess the change in hydrodynamic properties in comparison to the native valve. Herein, we report a platform for hydrodynamic testing of experimental aortic valve procedures that enables comparison with the native valve and between different devices and techniques used for the procedure under investigation.

We present a method for mounting a porcine aortic valve on a pulse duplicator to test its hydrodynamic properties. This method can be used to determine the change in hydrodynamics after the application of an experimental procedure or novel medical device prior to use in a large animal model.

The options for testing new cardiac procedures and investigative medical devices prior to use in an animal model are limited. In this study, we present a ...

生物工学

To begin, collect a fresh porcine cardiac specimen after cardiectomy. Dissect the pulmonary artery off the aorta with Metzenbaum scissors until ventricular tissue is visible. Then, dissect the right and the left coronary arteries, and ligate them using silk ties at their origin from the aortic sinuses without narrowing the sinuses.Transect the coronary arteries distal to the silk ties. Using Metzenbaum scissors, incise the right ventricle between the aorta and the pulmonary artery at the base of the pulmonary valve. Beginning anteriorly, continue the incision circumferentially along the intraventricular septum to remove the right ventricle free wall.Continue the incision posteriorly through the tricuspid valve annulus along the interatrial septum to remove all right atrial tissue. Next, using Metzenbaum scissors, incise the left atrium through the right pulmonary vein ostium parallel to the aorta. Continue this incision towards the anterolateral commissure of the mitral valve.Trim excess left atrium tissue while maintaining the three millimeter cuff of atrial tissue on the aorta and the mitral valve annulus circumferentially. Now, extend the incision onto the left ventricle through the anterolateral commissure of the mitral valve without damaging the anterolateral papillary muscle. Divide the chordae tendineae from the anterolateral papillary muscle to the posterior mitral valve leaflet, preserving attachments to the anterior mitral valve leaflet.Extend the incision to the apex of the heart. Trim excess left ventricle tissue below the papillary muscles, preserving both papillary muscles.

Mounting a Porcine Aortic Valve on a Pulse Duplicator for Testing Hydrodynamic Properties

After preparing the left ventricular outflow tract, or LVOT, trim any excess lymphatic, connective, or pulmonary artery tissue off the aorta. Using Metzenbaum scissors, incise the superior aspect of the aortic arch from the descending aorta to the left subclavian artery. Continue the incision on the superior aspect of the aortic arch from the left subclavian artery to the brachiocephalic trunk.To cannulate the LVOT, insert the fixture into the LVOT under the anterior leaflet of the mitral valve. Wrap the left ventricle free wall around the fixture and trim excess tissue to maintain a tight wrap around the fixture. Next, remove half the thickness of the left ventricle free wall, starting at the interventricular septum.Trim one centimeter of the tissue off the superior corner of the left ventricle free wall wrap. Place the fixture in the LVOT, so the supporting rod attachment hole is one centimeter behind the left ventricle incision. Using one or two six-inch zip ties, fasten the anterior leaflet of the mitral valve to the fixture positioned between the chordae tendineae of the leaflet.Next, using a taper point needle, suture the cuff of the left atrium tissue on the aorta to the mitral valve annulus. Continue the running stitch onto the left ventricle without tearing the tissue. Using Hegar Dilators, measure the diameter of the aortic valve.Then lift the specimen by grasping the aorta to identify the neutral position of the aorta. Insert the pulse duplicator or PD fixture into the aorta, ensuring the rod attachment holes are aligned with the neutral position of the aorta. Verify the specimen's length by inserting the support rods into the attachment holes.Using one or two six-inch zip ties, secure the PD fixture to the aorta. Then using screws provided with the PD set. Secure the support rods in place.Subsequently, secure the LVOT around the PD fixture using one or two eight-inch zip ties. Place the specimen in the PD and start the hydrodynamic testing. The values for hydrodynamic testing of the native aortic valve were within the normal range with a mean regurgitation fraction of 5.74%Hydrodynamic testing values showed no significant differences between formalin and glutaraldehyde fixed samples.After the Ozaki procedure, the values obtained with the control patch material suggested consistent valve replacement outcomes.